feat: 完善 Antigravity OAuth 功能与权限校验

新增功能：
- 实现 Antigravity OAuth 账户支持与路径分流
- 支持 /antigravity/api 路径自动分流到 Antigravity OAuth 账户
- 支持 gemini-antigravity 平台类型的账户创建和管理

修复问题：
- 修复 OAuthFlow 组件中 gemini-antigravity 平台授权页面空白的问题
- 修复 EditApiKeyModal 中 Redis 返回字符串格式 permissions 导致的 400 错误
- 统一使用 hasPermission 函数进行权限校验，支持数组格式

优化改进：
- 添加 Antigravity 调试环境变量说明

src/services/anthropicGeminiBridgeService.js

@@ -21,7 +21,10 @@ const SYSTEM_REMINDER_PREFIX = '<system-reminder>'
 const TOOLS_DUMP_ENV = 'ANTHROPIC_DEBUG_TOOLS_DUMP'
 const TOOLS_DUMP_FILENAME = 'anthropic-tools-dump.jsonl'
 const TEXT_TOOL_FALLBACK_ENV = 'ANTHROPIC_TEXT_TOOL_FALLBACK'
+const TOOL_ERROR_CONTINUE_ENV = 'ANTHROPIC_TOOL_ERROR_CONTINUE'
 const THOUGHT_SIGNATURE_FALLBACK = 'skip_thought_signature_validator'
+const TOOL_ERROR_CONTINUE_PROMPT =
+  'Tool calls may fail (e.g., missing prerequisites). When a tool result indicates an error, do not stop: briefly explain the cause and continue with an alternative approach or the remaining steps.'
 
 function ensureAntigravityProjectId(account) {
   if (account.projectId) {
@@ -710,12 +713,13 @@ function convertAnthropicMessagesToGeminiContents(
           if (vendor === 'antigravity') {
             const toolCallId = typeof toolUseId === 'string' && toolUseId ? toolUseId : undefined
             const result = parsedResponse !== null ? parsedResponse : raw || ''
+            const response = part.is_error === true ? { result, is_error: true } : { result }
 
             parts.push({
               functionResponse: {
                 ...(toolCallId ? { id: toolCallId } : {}),
                 name: toolName,
-                response: { result }
+                response
               }
             })
           } else {
@@ -761,6 +765,10 @@ function buildGeminiRequestFromAnthropic(body, baseModel, { vendor = null } = {}
   )
   const systemParts = buildSystemParts(body.system)
 
+  if (vendor === 'antigravity' && isEnvEnabled(process.env[TOOL_ERROR_CONTINUE_ENV])) {
+    systemParts.push({ text: TOOL_ERROR_CONTINUE_PROMPT })
+  }
+
   const temperature = typeof body.temperature === 'number' ? body.temperature : 1
   const maxTokens = Number.isFinite(body.max_tokens) ? body.max_tokens : 4096